The latest in sightseeing tours, brought to you by Count Ferdinand Von Zeppelin.

A windless day, sunlight filtered through high clouds. We are about 1,000 feet over south San Francisco in Eureka, the first zeppelin to fly over American soil since the Hindenburg explosion. In the gondola, a team of scientists from NASA’s Ames Research Laboratory in nearby Mountain View observes the hundreds of acres of coastal ponds below, a patchwork of vivid green, orange, and red.

Each pond has been isolated by levees from the action of tides; as the water in the ponds evaporates, a residue of salt is left behind. For a hundred years, the salt has been harvested by the Cargill Company. Now, a 15,000-acre parcel of this land has been returned to the state of California, to be restored to wetlands.

Eureka crisscrosses the ponds following precisely plotted tracks on its GPS. This is one of a series of flights over the area. "We’re part of a larger group that’s looking at the ecology of the [San Francisco] bay as we turn it from a salt pond back into a wetland," says Rocco Mancinelli, an Ames expert on halophiles, bacteria that thrive in extreme salinity. They hope to ease the disruption of the species that have adapted to the salty ponds.

The zeppelin has already demonstrated great promise for use in scientific research. Flying over Monterey Bay, it has studied how algae blooms can poison wildlife and has also tracked the route of a pipeline in an effort to detect how gas leaks underground change plant life on the surface.

The very qualities that make Eureka an outstanding airborne scientific observation platform—stability, maneuverability, lack of vibration, and ability to stay aloft for long periods and at low airspeeds—also make it superb at its day job: carrying sightseers on tours over California coastal regions, including San Francisco, Los Angeles, and San Diego.

In the distance we can see NASA’s Moffett Field, where three historic hangars for lighter-than-air craft rise up like monster cathedrals. Hangar One, which 76 years ago housed the Navy airship USS Macon, is now condemned because of toxic waste contamination. Directly across the runway is Hangar Two, Eureka’s home base. Here pilot Jim Dexter will ease the airship down to a mooring mast mounted on a truck parked in front of the hangar doors.

Eureka is owned and operated by Airship Ventures, Inc., founded by the husband-and-wife team of Brian and Alexandra Hall, president and chief executive officer, respectively. Brian, the founder and head of a Silicon Valley company, had always had an interest in flying. "I did start out my software career doing aviation software," he says. Alex, who has a degree in astrophysics, had directed the Chabot Space and Science Center in Oakland, California.

Brian, whose business trips often take him to Europe, became aware that an offspring of the original zeppelin company was stirring in Friedrichshafen, Germany. It was here, in 1900, that Graf (Count) Ferdinand von Zeppelin flew his first lighter-than-air craft. Over the years, 119 zeppelins were produced in the town.

The company that manufactured the original zeppelins, the ZF Group, is today a prosperous worldwide conglomerate, making automotive transmissions and steering and drive components but, for more than six decades, no zeppelins. Production of those ceased when the Hindenburg memorably exploded at Naval Air Station Lakehurst in New Jersey in 1937. After that, the world lost its appetite for zeppelins.

But in 1988, an event triggered the zeppelin’s rebirth. Friedrichshafen was celebrating the 150th anniversary of the count’s birth, and had asked the count’s great great grand nephew, Wolfgang von Zeppelin, a ballooning enthusiast, to fly his balloon during the celebration. In an e-mail from Germany, Wolfgang describes the genesis of a new generation of zeppelins: "I piloted the balloon," he says, "and my guest of honor in the balloon basket was the newly elected mayor, Bernd Widmann."